Scientists at the University of Cambridge have found that during the slow collision of tectonic plates, the Earth’s interior in subduction zones absorbs more carbon than previously thought. The study results will help develop new ways to save the planet from a climate catastrophe due to the increase in the concentration of carbon dioxide. This is reported in an article published in the journal Nature Communications.
Researchers have found that only a third of the carbon that circulates under the volcanic chains returns to the planet’s surface. Previously, it was believed that the flows balance each other and everything that gets into the mantle comes back. Instead, carbon enters the mantle in the form of carbon-containing compounds (for example, in the composition of mollusk shells and other organic residues) through subduction when some blocks of the earth’s crust sink under others. Some of this amount is then released through volcanoes.
It turned out that chemical processes occur in the mantle, trapping carbon in rocks and sending it deeper into the bowels of the Earth, preventing its return to the surface. This was shown by the results of experiments at the European Synchrotron Radiation Center. To simulate the pressure and temperature in the bowels of the Earth, scientists used a diamond anvil, in which a sample of carbon-containing rocks was placed. Carbonate rocks become less rich in calcium and richer in magnesium when they penetrate deeper into the mantle. As a result, the solubility of the carbonate decreases, and it does not enter the liquid environment under active volcanoes. Instead, the carbon sinks deeper into the mantle, where it can turn into a diamond.
According to the scientists, their study shows that carbonate rocks effectively absorb carbon and store it for a long time. A group of researchers is currently studying the possibility of using similar methods to capture carbon from the atmosphere into rocks and oceans, which may be useful to combat the increase in greenhouse gas concentrations.